Battery electrodes with enlarged surfaces and method for production thereof

Abstract

According to the invention, a method for the production of battery electrodes and battery electrodes produced with this method are provided, whereby the method comprises the production of compositions of the electrode materials for cathode or anode material and, if required, a separator material, and the extrusion of the electrode material to form the anode or cathode from the electrode material, and is characterized in that the electrode material comprises isocyanate and an aqueous dispersion of a polymer binder which react with one another to form porous structures. By means of the method according to the invention, extremely elastic and, at the same time, mechanically stable battery electrodes are generated that may be utilized in lithium secondary batteries.

1 . A method for producing an extruded electrode material for use in a battery, the method comprising: 
 extruding a cathode material composition or an anode material composition, said composition comprising isocyanate and an aqueous dispersion of a polymer binder wherein    the isocyanate reacts with the aqueous dispersion of the polymer binder to form an extruded electrode material having a porous structure.    
   
   
       2 . The method according to  claim 1 , wherein the isocyanate is selected from the group consisting of di-, tri-, and polyisocyanates.  
   
   
       3 . The method according to  claim 1  wherein the isocyanate is selected from the group consisting of isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-bis(3-isocyanato-4-methylphenyl)-2,4-dioxo-1,3-diazetidine), a reaction product of poly(butene adipate) and a mixture comprising 65% toluene 2,4-diisocyanate and 35% toluene 2,6-diisocyanate, and naphthalene 1,5-diisocyanate.  
   
   
       4 . The method according to  claim 1 , wherein the polymer binder is selected from the group consisting of polyolefins, polyethylene, polypropylene, polyisobutene, polystyrene, rubbers based on styrene/butadiene, rubbers based on isoprene, and a fluoroelastomer.  
   
   
       5 . The method according to  claim 4 , wherein the aqueous dispersion of the polymer binder comprises a nonionic emulsifier comprising a perfluorocarboxylic acid having more than 6 carbon atoms.  
   
   
       6 . The method according to  claim 1 , wherein the extruded electrode material comprises an open-porous structure.  
   
   
       7 . The method according to  claim 1 , wherein the extrusion of the anode material composition or the cathode material composition occurs at temperatures of 80 to 180° C.  
   
   
       8 . The method according to  claim 1 , further comprising the step of laminating the extruded electrode material to a current collector film.  
   
   
       9 . The method according to  claim 1 , wherein the isocynate comprises 0.5 to 10 percent by weight of the anode material composition or the cathode material composition.  
   
   
       10 . The method according to  claim 1 , wherein the aqueous dispersion of the polymer binder comprises 1 to 15 percent by weight of the anode material composition or the cathode material composition.  
   
   
       11 . The method according to  claim 1 , wherein the anode material composition comprises carbon.  
   
   
       12 . The method according to  claim 1 , wherein the cathode material composition comprises a metal oxide.  
   
   
       13 . The method according to  claim 1 , wherein the anode material composition or the cathode material composition comprises one or more additives selected from the group consisting of fillers, acid catchers, inhibitors, amines, activators in organotin compounds, and Lewis bases.  
   
   
       14 . The method according to  claim 13 , wherein the additives comprise 0.01 to 1 percent by weight of the anode material composition or the cathode material composition.  
   
   
       15 . The method according to  claim 8 , wherein the laminating occurs at pressures of 2-10 bar.  
   
   
       16 . The method according to  claim 1 , wherein the extrusion occurs in an extruder and the aqueous polymer dispersion is pumped into a feed zone of the extruder at temperatures of 20-100° C.  
   
   
       17 . The method according to  claim 1 , wherein the extruded electrode material is removed through a slit die of an extruder having a width of 30 to 500 mm and a thickness of 5 to 1,000 μm.  
   
   
       18 . The method according to  claim 1 , wherein the extruded electrode material comprises a porous film.  
   
   
       19 . A method for producing a battery, the method comprising: 
 providing a cathode formed from the extruded material produced according to the method of  claim 1;     providing an anode formed from the extruded material produced according to the method of  claim 1;     disposing a separator between the anode and the cathode to form a composite;    laminating the composite; and    applying electrical contacts to the composite to form the battery.    
   
   
       20 . The method according to  claim 19  wherein the battery separator comprises a porous structure.  
   
   
       21 . A battery electrode comprising an extruded electrode material produced according to the method of  claim 1 .  
   
   
       22 . The battery produced according to the method of  claim 19  wherein the battery is a secondary lithium battery.  
   
   
       23 . The method according to  claim 4 , wherein the polymer binder is selected from the group consisting of a copolymer of a fluoroelastamer and terpolymer of a fluoroelastomer.  
   
   
       24 . The method according to  claim 23  wherein the terpolymer comprises tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride.  
   
   
       25 . The method according to  claim 4 , wherein the aqueous dispersion of the polymer binder comprises a perfluorocarboxylic acid salt having more than six carbon atoms.  
   
   
       26 . The method according to  claim 4 , wherein the aqueous dispersion of the polymer binder comprises a fluoropolymer.  
   
   
       27 . The method according to  claim 26 , wherein the fluoropolymer is selected from the group consisting of a copolymers of a fluoropolymer and a terpolymer of a fluoropolymer.  
   
   
       28 . The method according to  claim 7  wherein the extrusion of the anode material composition or the cathode material composition occurs at a temperature of 120 to 140° C.  
   
   
       29 . The method according to  claim 11  wherein the carbon in the anode material composition comprises intercalatable carbon.  
   
   
       30 . The method according to  claim 11  wherein the carbon in the anode material composition comprises graphite.  
   
   
       31 . The method according to  claim 12  wherein the metal oxide in the cathode material composition comprises an intercalatable metal oxide.  
   
   
       32 . The method according to  claim 12  wherein the metal oxide is an oxide of a metal selected from the group consisting of manganese, nickel, cobalt, titanium, chromium, molybdenum, and tungsten.  
   
   
       33 . The method according to  claim 13  wherein the fillers comprise SiO 2 .  
   
   
       34 . The method according to  claim 13  wherein the inhibitors are selected from the group consisting of MgO and Al 2 O 3 .  
   
   
       35 . The method according to  claim 13  wherein the Lewis bases comprise 1,4-diazabicyclo[2.2.2]octane.